Problem: A pen and its ink refill together cost $\;\$1.10$. The pen costs $\;\$1$ more than the ink refill. What is the cost of the pen in dollars?
Answer: Begin by assigning variables.  Let $p$=the cost of the pen and $i$=the cost of the ink.  From what we are given,
\begin{align*}
p+i&=1.10,\\
p&=1+i.
\end{align*} Substituting for $p$ in the first equation, we find: $1+i+i=1.10$, so $2i=.10$ and $i=.05$. Therefore, $p=1+i=\boxed{1.05}$ dollars.